Fans : How many blades?

[G. Morgan]

WTF???

[blueman]

:) for the humor impaired - I thought it was LMAO funny...

[E Z Peaces]

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Aha, some of these fans rotate a lot faster than aircraft propellers. The 75" prop on a Cessna 172 can rotate up to 2700 rpm. Usually, it's undesirable for the tip to exceed the speed of sound, so bigger props are likely to have reduction gears to rotate slower.

[E Z Peaces]

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Rats, I misread the Mcmaster data. They don't turn faster than a Cessna

172 but do turn faster than larger propellers.

[mm]

But true. That's what he told me. I felt like I was a girl with a guy lying to me about his intentions.

I thought we were just having dinner together at one of those very low cost buffets in Las Vegas, until he started paying me compliments. I felt like a girl then too.

Anyhow I slept on the sofa.

[mm]

No of course not. This is all nonsense. Keep the fan still and rotate the house.

[Red Green]

"Bob-tx" wrote in news:4a68c053$0$23774$bbae4d71 @news.suddenlink.net:

Ideal number of blades is, of course, 42.

[Wayne Boatwright]

On Thu 23 Jul 2009 01:56:01p, Bob-tx told us...

Two, three, four, or five blades matters far less than the CFM (cubic feet of air per minute) delivered at all speeds, usually three. The number of blades is often more an issue of aeshtetic preference than performance. Other factors such as the degrees pitch of the blades and the RPM determine how much air is delivered.

We have seven ceiling fans in our house, ranging from a top price of around $600 down to one that costs only $70. The high end fans have five blades (54" blade span) and were chosen not ony for performance but also for aesthetics and motor warranty. The least expensive fan is smaller (42" blade span), has a smaller motor, shorter warranty, and delivers somewhat less air, but it was ideal for the location it was selected.

Do you homework... You'll rarely get a good answer from store personnel unless it's a fan specialty store with well-educated staff.

[Plague Boy]

No, the two-bladed fan is most efficient, but *only* when you coat both blades with WD-40.